Seasonal Climate Outlook Message for December 2004 to March 2005

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Climate Watch 01/12/04

SOI Remains Near Zero

For the fourth month in a row the SOI has remained in a "Consistently Near Zero" phase.

By comparing the SOI phase at the end of November and historical rainfall records, the chance of getting above median rainfall for December through to the end of February for most of Queensland is predominately between 40 to 60%.

For example Winton has a 48% chance of getting above its long-term December to February median rainfall of 195 mm, Dalby has a 46% chance of getting above its long-term December to February median rainfall of 245 mm, Gatton-Lawes has a 50% chance of getting above its long-term December to February median rainfall of 305 mm and both Townsville and Mackay have around a 50% chance of getting above their long-term December to February median rainfall of 625 and 765 mm respectively.

For there to be an overall improvement in the seasonal outlook for Queensland, it would help if the SOI rose to a "Consistently Positive" pattern for a couple of months at least. Daily updates on the SOI are available on (07) 46881439.

Similar to rainfall probabilities in Queensland, there is a predominately 40 to 60% chance of getting above the long-term December to February median rainfall across the rest of Australia. The higher rainfall probabilities (60 to 70%) can be found mainly in the western half of Victoria, coastal South Australia and parts of the north-west of Australia.

This forecast doesn't indicate the potential distribution or expected timing of rainfall over this period. The forecast is for a full 3 month period and doesn't suggest that any expected rain will fall evenly across these 3 months.

Many people like to follow the relationship between the SOI and rainfall patterns in more detail. To do that, have a look at what happened in your area over December to February in the following years; 2003, 2002, 1996, 1995, 1990, 1985, 1983, 1980, 1979, 1978, 1968, 1967, 1966, 1958, 1954, 1953, 1952, 1945, 1937, 1932, 1931 and 1930 and compare the rainfall recorded with your 'normal' rainfall for December to February.

For example, during December to February at Emerald in those years, above average rainfall was recorded 9 times, near average rainfall was recorded 7 times and below average rainfall was recorded seven times. At Roma, above average rainfall was recorded 8 times, near average rainfall was recorded 4 times and below average rainfall was recorded 11 times.

The full story

Climate Watch 01/12/04

SOI Remains Near Zero

Based on the shift in value of the SOI from the end of October (minus 3.2) to the end of November (minus 7.7), the SOI is in a "Consistently Near Zero" phase. This is the fourth month in a row the SOI has remained in a "Consistently Near Zero" phase.

By comparing the SOI phase and historical rainfall records, the chance of getting above median rainfall through to the end of February for most of Queensland is predominately between 40 to 60%.

For example Winton has a 48% chance of getting above its long-term December to February median rainfall of 195 mm, Dalby has a 46% chance of getting above its long-term December to February median rainfall of 245 mm, Gatton-Lawes has a 50% chance of getting above its long-term December to February median rainfall of 305 mm and both Townsville and Mackay have around a 50% chance of getting above their long-term December to February median rainfall of 625 and 765 mm respectively.

For there to be an overall improvement in the seasonal outlook for Queensland, it would help if the SOI rose to a "Consistently Positive" pattern for a couple of months at least. Daily updates on the SOI are available on (07) 46881439.

Similar to rainfall probabilities in Queensland, there is a predominately 40 to 60% chance of getting above the long-term December to February median rainfall across the rest of Australia. The higher rainfall probabilities (60 to 70%) can be found mainly in the western half of Victoria, coastal South Australia and parts of the north-west of Australia.

This forecast doesn't indicate the potential distribution or expected timing of rainfall over this period. The forecast is for a full 3 month period and doesn't suggest that any expected rain will fall evenly across these 3 months.

The latest rainfall probability maps for Queensland, Australia and the world are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au

In a recent media release the Bureau of Meteorology www.bom.gov.au stated that based on the best available and most recent information the lengthy run of relatively quiet cyclone seasons was likely to continue for Queensland with the number of tropical cyclones in the Coral Sea this season having only an outside chance of exceeding 2 or 3, and not all will cross the coast.

In a reflection of the lack of cyclone activity the Bureau also state that the last 15 years have been relatively quiet in terms of both cyclone activity in the Coral Sea and the incidence of significant cyclone impacts along the Queensland coast with the past 3 cyclone seasons being particularly unusual in that only 1 cyclone has crossed the east Queensland coast ("Fritz" a low Category 1 in the far north last February).

For more information on cyclones try the Queensland Tropical Cyclone Warning Centre at www.bom.gov.au/weather/qld/cyclone

Many people like to follow the relationship between the SOI and rainfall patterns in more detail. To do that, have a look at what happened in your area over December to February in the following years; 2003, 2002, 1996, 1995, 1990, 1985, 1983, 1980, 1979, 1978, 1968, 1967, 1966, 1958, 1954, 1953, 1952, 1945, 1937, 1932, 1931 and 1930 and compare the rainfall recorded with your 'normal' rainfall for December to February.

For example, during December to February at Emerald in those years, above average rainfall was recorded 9 times, near average rainfall was recorded 7 times and below average rainfall was recorded seven times. At Roma, above average rainfall was recorded 8 times, near average rainfall was recorded 4 times and below average rainfall was recorded 11 times.

As with any probability based forecast system it is important to consider the opposite aspect. For example Charters Towers has around a 70% chance of getting above 270 mm over December to February. This also means that there is a 30% chance of NOT getting the 270 mm over December to February.

Another way of looking at this is in around 7 years out of 10 (or around three quarters) with the current SOI pattern, Charters Towers has received at least 270 mm over December to February. Therefore in 3 years out of 10 (or around one quarter), Charters Towers has gotten less than 150 mm over December to February.

The last active phase of the MJO across Australia occurred in early November helping trigger some useful falls. It has currently weakened and appears to have stagnated. Until it re-establishes, predictions based on the MJO will be more difficult. However if its timing remains current it will next be expected in mid to late December.

The MJO is simply a band of low air pressure originating off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 60 days. Research has shown the MJO to be a useful indicator of the timing of potential rainfall events across much of Queensland. Given the growing interest in the MJO, and with funding from the DPI&F, GRDC and CRDC we have developed a site www.apsru.gov.au/mjo/ that will allow anyone interested to track its passage.

At present, sea surface temperatures (SST) in the Pacific are not in a classic El Niño pattern such as occurred from mid 2002 to mid 2003. However, from a risk management view point, the fact that SST in the central Pacific from the international dateline running east are warmer than normal (+0.5 to 1.5oC) is cause for concern.

Research has shown that it is the central part of the Pacific Ocean that has a major impact of our seasonal outlook. When SST in this region are warmer than normal, there is an increased risk that our rainfall and water supply across eastern Australia will be below average. We are describing this pattern as a "border line El Niño".

As an example, in 1992 and 1993 a borderline El Niño sea surface temperature pattern could be found in the Pacific. Both of these years produced below average rainfall for large parts of Queensland but not to the extent of the 2002/2003 El Niño event. To find out more on conditions in the Pacific try the Bureau of Meteorology "El Niño wrap up" at www.bom.gov.au/climate/enso/ or the US Climate Prediction Centre at www.cpc.ncep.noaa.gov/ For the latest sea surface temperature maps have a look at www.cpc.ncep.noaa.gov/products or at www.longpaddock.qld.gov.au/

When incorporating climate forecasts into management decisions, it could be worthwhile to consider some of the following general rules of thumb developed from feedback from climate users.

1. The first point is to be sure of your source of information and what it is actually suggesting. Do not take a quick grab of information from any source including radio, TV or the internet and assume what you heard/saw/read applies to your location.

2. Management decisions should never be based entirely on one factor (such as a weather or climate forecast). As always, all factors that could impact of the outcome of a decision (such as soil moisture/type, crop, pasture type/availability, commodity prices, machinery, work force, transport, finance, costs, seasonal outlook etc) should be considered.

3. Try to access local information or at least be aware of the long-term median for your location so you can correctly interpret the forecast.

4. It has also been shown to be useful to do a cost benefit analysis of any decision with a climate risk factor eg What will I gain if I get the desired outcome from this decision? What will I lose if I don't get the desired outcome from this decision? What other cost neutral options do I have if any?

5. Do not to take a forecast for a specific period (eg September to November) and expand it out (eg late summer). Update the information regularly.

An interesting site www.cvap.gov.au/mastersoftheclimate/ from the 'Climate Variability In Agriculture' (CVAP) research and development program is well worth looking at. It highlights some case studies on how producers and businesses have used (to varying levels of success) climate and weather information in their decision making processes.